Washers are reusable.Size: 1/4 inch X 5/8 inch Outer DiameterMetal washer with layer of neoprene rubber on one sideMetal side provides strength while rubber side creates a secure water resistant sealNeoprene rubber seal also helps protect against corrosionGreat for use in plumbing or outdoor applications such as roofingSpecification(s) Met: ASTM A653 TYPE B Made of neoprene rubber, the seal produces good oil and abrasion resistance.Sealing Washer, Fits Bolt Size 1/4 in EPDM/Steel, Galvanized Finish, 25 PK Bonded sealing washers also provide more corrosion protection compared to standard washers..